Cellular Function

What are the main cellular structures and their functions?

• Cell Membrane - Outer boundary, selectively permeable

• Cytoplasm - Gel-like substance filling the cell

• Organelles - Specialized structures within the cell

• Nucleus - Contains genetic material, controls cell activities

• Cytoskeleton - Provides structural support and shape

What are the five basic cellular functions?

1. Cell metabolism and energy use

2. Synthesis of molecules

3. Communication

4. Reproduction

5. Inheritance

How do cells exchange materials across the plasma membrane?

Plasma membranes are selectively permeable

Passive Transport (no energy required):

• Simple Diffusion - Movement from high to low concentration

• Facilitated Diffusion - Uses transport proteins

Active Transport (energy required):

• Moves substances against concentration gradient

Bulk Transport:

• Endocytosis - Bringing substances INTO the cell

• Exocytosis - Releasing substances OUT of the cell

• Pinocytosis - "Cell drinking" (fluid intake)

• Phagocytosis - "Cell eating" (solid particles)

What is step 1 of the process of energy production in cells?

Step 1: Breakdown of Macromolecules

• Glucose → Glycolysis (converts glucose)

• Fatty Acids → Fatty Acid Oxidation

• Amino Acids → Amino Acid Oxidation

What is step 2 of the process of energy production in cells?

Step 2: Formation of Acetyl-CoA

• All broken down molecules create Acetyl-CoA (enzyme-mediated)

What is step 3 of the process of energy production in cells?

Step 3: Citric Acid Cycle (Krebs Cycle)

• Occurs in the mitochondria

• Complex series of reactions

• Requires oxygen

• Produces CO₂ and H₂O as waste

What is step 4 of the process of energy production in cells?

Step 4: End Product = ATP (cellular energy)

What is mitosis?

cell division

What are the characteristics of mitosis?

Key Points:

• Produces 2 genetically identical cells

• Average cell divides 50-70 times before dying

• Telomeres (ends of DNA) get shorter with each division

• Process is regulated

Proliferation:

• Some cells divide continuously

• Some rarely divide

Affected by:

• Genes

• Growth factors

• Environmental factors (chemical exposure, nutrition, infections)

What are the embryonic stem cells, their characteristics, and derivatives?

• pluripotent

• can develop into over 200 cell types

• derivatives: endoderm, ectoderm, mesoderm

What are the adult stem cells, their characteristics, and derivatives?

• multipotent

• can differentiate into specific cell types

• hematopoietic, epithelial, neuronal, mesenchymal

What are the three germ layers derived from embryonic stem cells?

1. Endoderm

2. Ectoderm

3. Mesoderm

Name the types of cellular adaptation and damage.

• atrophy

• hypertrophy

• hyperplasia

• metaplasia

• dysplasia

atrophy

• decrease in size and number when decreased demand

Hypertrophy

increase in size to meet increased demand

Hyperplasia

increase in number of cells in a tissue/organ

metaplasia

replaced by another cell type in response to chronic irritation

dysplasia

cells mutate into a different size, shape, type due to trigger, precancerous

What are the key points of cellular adaptation and damage?

• Cells protect themselves through adapting

• Modifications help manage changes and maintain homeostasis

• May be permanent or reversible

• Can become abnormal (disease)

What are the common causes of cell injury?

1. Physical - Mechanical trauma, temperature extremes

2. Chemical - Pollution, lead, drugs

3. Radiation - Ionizing and non-ionizing

4. Biological agents - Viruses, bacteria, parasites

5. Low oxygen levels - Hypoxia

6. Nutritional imbalances - Metabolic waste accumulation, ATP depletion

What is the difference between reversible and irreversible cell injury?

Normal Cell → Stress → Cell Injury

Reversible Injury:

• Cell can recover and return to normal

• Includes Adaptation responses

Irreversible Injury:

• Cell cannot recover

• Leads to Cell Death (Necrosis or Apoptosis)

What is apoptosis?

Programmed cell death

What are the characteristics of Apoptosis

• Eliminates unwanted, injured, dead cells

• Cell self-destructs and breaks into fragments

• Fragments are ingested by macrophages

• Normal process of a living organism

• Does NOT initiate inflammation

What is necrosis

Cell Swells and burst

• Initiates inflammatory response

Name the types of Necrosis

• liquefaction

• caseous

• fat

• coagulative

Describe Liquefaction of necrosis and give an example

Enzymes dissolve cells and liquify tissue

• example: Brain, ischemic stroke

Describe caseous of necrosis and give an example

Cell debris solidifies (cottage cheese-like)

• Example: Tuberculosis

Describe fat of necrosis and give an example

Lipase enzymes break down triglycerides; FFA bind with ions creating soaps

• example: breast injury, pancreatitis

Describe coagulative of necrosis and give an example

Due to lack of blood flow; tissue becomes acidotic (low pH); cellular enzymes denature

• Example: Kidneys, heart, adrenal gland

What is gangrene?

Type of necrosis

What are the characteristics of gangrene?

• Common in lower extremities

• Due to peripheral arterial disease (atherosclerosis)

• Combination of impaired blood flow and bacterial infection

What are the types of gangrene?

• Dry

• Wet

• Gas

What is carcinogenesis

Process of cancer development

What are the three phases of carcinogenesis and describe them

1. Initiation - Exposure to carcinogen, DNA mutation occurs

2. Promotion - Mutated cells exposed to factors that promote growth

3. Progression - Cancer cells grow and invade surrounding tissues; can metastasize or become resistant to treatment

What is metastasis?

Spread of cancer cells from primary site to distant locations

Where are the common sites of metastasis?

• Follows blood flow and lymphatic drainage

(Brain, lung, liver, bone, Adrenal Gland)

What are the signs of cancer advancing/Progressing?

• Anemia

• Cachexia

• Fatigue

• Infection

• Leukopenia

• Thrombocytopenia

• Pain

What are the two types of tumors?

• benign

• malignant

Describe a benign tumor

Cell appearance: Relatively normal cells

Replication: high replication rate but controlled

encapsulation: encapsulated

invasion: does NOT penetrate nearby tissues

Metastasis: low likelihood

Describe a malignant tumor

Cell appearance: anaplastic (abnormal), non-functional cells

Replication: uncontrolled division

encapsulation: not encapsulated

invasion: penetrates nearby tissues

Metastasis: more likely to metastasize

What is the TNM cancer staging system?

• T = Tumor (size and extent of primary tumor)

• N = Node (lymph node involvement)

• M = Metastasis (spread to distant organs)

Describe the cancer stages from 1 thru 4

• Stage 1 - Non-invasive, minimal differentiation

• Stage 2 - Invading local tissues

• Stage 3 - Metastasized to local lymph nodes

• Stage 4 - Invasive and metastasized to other organs

What are the signs/symptoms of cancer? (CAUTION)

C - Change in bowel or bladder habits
A - A sore that doesn't heal
U - Unusual bleeding or discharge
T - Thickening or lump in the breast or elsewhere
I - Indigestion or difficulty swallowing
O - Obvious change in a wart or mole
N - Nagging cough or hoarseness

What are the common treatments for cancer? and what are some of the goals?

Goals: Curative, Palliative, Preventative

1. Chemotherapy - Destroy replicating cells

2. Radiation - Target cancer cells and blood supply

3. Surgery - Remove cancer until clear margins

4. Targeted therapy - Specific molecular targets

5. Hormone therapy - Block hormones that fuel cancer

6. Immunotherapy - Boost immune system

7. Laser/Hyperthermia - Heat/light to destroy cells